1. Field of the Invention
The present invention relates to the field of electrical wiring installations. More particularly the present invention relates to the field of spacing means used in conjunction with electrical wiring boxes and screw fastening means.
2. Description of The Prior Art
When installing indoor electrical switch and outlet plates on the walls, electrical wiring boxes are often placed inside the walls behind the electrical plates. Electrical wiring boxes are usually square shaped metal box frames with various openings and holes for mounting with screws and running electrical wires.
Today the dividing walls in homes and offices typically have a hard central portion and a surface portion. The hard central portion is the major part of a wall which stands the stress, and is what is ordinarily called the "wall". The surface portion, often called "dry wall", is the exposed part which is later placed as a covering onto the center portion of the wall for decoration and other purposes, and is usually made of tile or similar light material. In the following discussion if not otherwise specified, the word "wall" is used to specify the central portion of a wall, and the word "dry wall" is used to specify the surface portion of a wall.
Referring to FIGS. 1 and 2, in the practice of indoor electrical installations, first a square shaped chamber 12 is cut out from a wall 10. The size of chamber 12 is usually greater than the size of commercial electrical wiring boxes. An electrical wiring box 30 is then placed into chamber 12. Electrical box 30 often has receiving arms 32 and mounting arms 31 with screw holes. Mounting arms 34 can be fastened to an edge 14 of chamber 12 by using fastening screws to tightly mount electrical box 30 to wall 10. After electrical box 30 is installed into wall 10, a dry wall 20 is placed over wall 10, and an opening 22 is cut out at the position of electrical box 30 for installing electrical wall plates such as electrical switch plates or power outlet plates. FIG. 1 shows an example of an electrical power outlet plate 40. Usually electrical plate 40 has mounting arms 42 with screw holes. If there is no dry wall 20, mounting arms 42 of electrical plate 40 may be directly brought into contact with receiving arms 32 of electrical box 30 and fastened by screws. However it becomes difficult to mount the power outlet plate 40 since dry wall 20 has a certain thickness. The exposed surface 44 of electrical plate 40 is supposed to be in the same plane with the exposed surface 24 of dry wall 20, or even further extends out a little bit, which leaves a gap between a mounting arm 42 of electrical plate 40 and a respective receiving arm 32 of electrical box 30, as shown in FIG. 2. If opening 22 of dry wall 20 is cut right in size, mounting arms 42 of electrical plate 40 can probably be mounted by screws directly to exposed surface 24 of dry wall 20 near the edge of opening 22. Unfortunately, sometimes opening 22 is made too large which makes it impossible to mount mounting arm 42 of electrical plate 40 directly onto exposed surface 24 of dry wall 20. Therefore mounting arms 42 of electrical plate 40 have to be screwed to receiving arms 32 of electrical box 30, even if there is a gap in between.
In the prior art, electricians either wrap a lot of wire around the screws or, alternatively, use other shims such as rings of washers to provide means with a certain thickness to fill the gap. These conventional approaches are both inconvenient and unstable. It will be very beneficial if there is a spacer means that can be easily applied in this situation.